Humidity in the hatcher
LOOK-THINK-ACT
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The fresh air demand increases and moisture is very important to ensure the eggshell membranes remain soft and supple, so that the chick can free itself during hatching. Preferably let the chicks dry off in the hatcher as this avoids stress caused by cooling down too quickly. After external pipping, each chick evaporates an amount of water equivalent to 3% of the original egg weight. And once the chick hatches and dries off, it evaporates another 3%. The humidity may rise then, but this is a natural development. If you leave the RH setpoint at the original level (and base climate control on the RH), there will be too much ventilation (and chicks will cool down too much), or the system will continually give an alarm. The aim here is to extract moisture, rather than add it. When the humidity level drops again, this is a sign that no more chicks are hatching, and that all the chicks are drying off. The chicks can be pulled between 10 and 12 hours after the humidity peak.
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Is it a good idea to use spraying during hatching, to facilitate the process?
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No, this is not a good idea during hatching. The RH should remain constant. Hatcheries sometimes use spray to humidify, but it is risky. The chicks actually need to dry off. Otherwise, there is a risk of wet spots and cold chicks. When using sprays, they are often activated for 20 seconds every 5 minutes. Weight loss of chicks is lower, but sometimes it slows down the hatching process in some trays. And adding water involves the additional hazard of E-coli infection. Disinfectant in the humidity nozzle decreases the risk of contamination. It is much better to condition the fresh air supply to the right temperature and humidity levels. Depending on the design of the ventilation system and hatcher, an air temperature of 22-24°C and RH of 5070% are maintained.
Changing parameters in the hatcher
Temperature (°F)
co
100
98
97
80 60
RH (%) 99
100
ventilation air inlet position (%) hatcher temperature (°F)
40
CO2 concentration 20
hatch peak: RH 57%, until end of humidity peak (= peak - 3%) 02.00 p.m 10.00 p.m. 06.00 a.m. 02.00 p.m. 10.00 p.m. Time of day
0
Once the chicks begin external pipping, the RH spontaneously rises quickly. A slightly higher RH makes it easier for the chicks to hatch. However, humidification is not necessary, because a lot of moisture is released during hatching (blue line = humidity peak). Just after the chicks hatch, the RH drops again to 50-55%, so that they can dry off properly. The CO2 concentration used to control the inlet position is the guiding factor here. A lot of CO2 is released, and the ventilation inlets are opened to a higher position (green line) to maintain the required concentration. 134
RH and ventilation air inlet position (%)
humidity peak higher ventilation setting removes start of moisture humidity peak
101
The humidity level rises during hatching. But the walls and floor must remain as dry as possible. A wet floor combined with fluff and down offers an ideal environment for bacteria.
Fluff in the hatcher is a good signal. A lot of fluff is usually associated with a short hatch window. A short and intense hatch window like this usually results in high hatchability. Which is why we say: lots of fluff = good hatchability. Ha tc he ry S i gnal s
